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This snippet of info. was posted to VSNET today by Keisuke Isogai…
“The object faded to 16.4 mag on May 5. This object will (or has already)
show a long-term rebrightening with a duration of about 10 days. We will
be able to observe superhumps in the rebrightening phase. Because the
superhump period in the rebrightening may be different from that in the
main superoutburst, continuous observations are encouraged.”Gary
AL Com has dropped two magnitudes in just two days. I had a 16.3 estimate last night in a cloud break. Typical UGWZ behaviour. I wonder if it will pop back up?
Gary
Mike,
Your correct – there isn’t a lot out there on AL Com. There is this from 2001 which you might find interesting…
First detection of the growing humps at the rapidly rising stage of dwarf novae AL Com and WZ Sge Ishioka et al…
https://www.aanda.org/articles/aa/pdf/2002/03/aadj293.pdf
You will probably need to read up on UGSU or UGWZ stars to find a direct reference to AL Com. Taichi Kato et al has written a series of papers entitled “Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae” in which AL Com is included. I think there are currently nine papers in this series so far.
Hopefully the observations are being reported to the VSS database – although a look this morning suggests that some haven’t been uploaded yet. So far we have M. Joslin and myself visual and I. Miller, M. Mobberley and R. Pickard CCD – with Miller and Pickard reporting time series. I envisage a report on the outburst once it’s over appearing in a future VSS Circular.
Gary
I’m continuing to monitor it visually, and my last observation was Apr 25.98 UT at 14.2 so it’s fading gradually now.
Very probably the magnitude will drop quickly once it gets just below 15ish, but this might not be the end of the outburst. UGWZ stars very often (but not always) have ‘echo’ outbursts or rebrightenings. AL Com has a history of this. Since 1995, three of the outbursts detected have showed this phenomenon, but the 1995 one was the best. It was the first outburst of AL Com observed with the ‘new’ CCD’s, and showed two rebrightenings after the primary outburst had finished. One rebrightening was seen in each of the 2013 and 2015 outbursts.
The light curve shown here is of the 1995 outburst, and was compiled by me during my BAAVSS directorship from observations from observers around the world. The two post outburst events can be seen clearly.
So, if your following AL Com at the moment and you lose it either visually or with your CCD, continue to monitor for a couple of weeks longer. There is no guarantee it will brighten again but it just might…
Gary
The scopes are C14’s.
The value of unfiltered measurements is immense. See the number of papers in the BAAJ or other (professional) journals which contain unfiltered data from amateurs to see just how important they are.
Simple patrolling for outbursts for example – deeper images unfiltered or less exposure time. Time series observations during outburst are just as valuable unfiltered – it’s the period and amplitude which are important here, not necessarily the intrinsic brightness. And of course, an unfiltered observation is better than no observation at all!
Gary
I’ve picked it up a few times at minimum with the old BRT and new COAST telescopes, unfiltered and 60-80 seconds exposure varying between 18.5-19.5. It has quite a range at quiescence ~18.5-21.00. Seen a few outbursts visually too. More exciting than ogling the galaxy 😉
Gary
You might also try it’s alternate designation of IRAS 051853227.
There are a few pages where it’s listed in Kenyons classic book ‘Symbiotic Stars’. If you contact me off-list, I’ll copy the relevant pages for you – but the book is still available and it’s worth owning.
Good luck,
Gary
David,
If there is any fog to be burned off, it’s concentrating on Birmingham first but alas it just predicts. I too want to see ASASSN-19de (easier to write than the TCP designation).
Good luck
Gary
I remember seeing it in the late 1970’s visually with a 10inch F6.5 newtonian. It could have been 1978-79 but I’m having trouble locating that observation in my files (which is why I’m late to the discussion). I do recall that it was a very difficult observation to make, with the separation at or near maximum distance I think. If I find my notes, I’ll come back. Don’t think I dreamt it!
Gary
Happy New year Jeremy, and to all BAA members reading this.
A far better year than 2017 – which wasn’t too difficult to achieve.(2016 in brackets)North Birmingham.Clear nights (less than 50% cloud) 44 (25), Partially clear nights (50% or more cloud) 69 (61)Total observable nights 113 (86) with 55 of these nights being under Moonlight conditions. I made variable star observations on 108 of these 113 nights. This is my best year for clear nights since 2003.Total hours at the telescope: 237.3 (183.6)Best month May (March) 6 clear and 12 partially clearWorst month March (February) 2 clear and 2 partially clearOn 53 nights of the year, Birmingham Met Office gave the wrong prediction for cloud cover. This is a six night improvement on 2017. My weather owl did much better!My total visual VS observations for 2018 is 9,013 – the best year since 2009. It was a poor year for remote CCD observations though with only 1,767 observations obtained. This was due to the Open University COAST telescope being out of commission for most of the year, and a prolonged Monsoon in the SW USA which affected the AAVSOnet SRO-50 reflector in Arizona. All CCD observations were of variable stars – of course.2018 was memorable for me as I passed my 300,000th visual VS observation in October.GarySpeaking personally, I wouldn’t want to see the Winchester weekend moved. Travelling down to Winchester in early Spring has become a bit of a habit for me – 41 years now. The location is good (nice and rural for a city dweller like me). I enjoyed the Warwick meeting of course, but Winchester remains my favourite astro-meet of the year!
Gary
Now now James. We had to give Nick something interesting to talk about!
Just like to thank the BAA for putting on another excellent Christmas meeting. Thank you all for your hard work and well done!
The IOP is a terrific venue, and I look forward to more meetings there in the future.
Gary
Indeed Andy.
I didn’t want to post the alert twice – variable stars and spectroscopy – and as X Per is a VS, that (to me) was the correct place to post it!
Gary
Good to see people are monitoring this one. My first visual estimate last night was 15.0 in a poor sky.
I’ll ask Andy to add this object to the BAAVSS database.
Gary
